(a) Field of the Invention
The present invention relates to a closed crankcase ventilation apparatus, and more particularly, to a closed crankcase ventilation apparatus that exhausts blow-by gas from a crankcase effectively and thereby prevents pressure in a crankcase from excessively increasing.
(b) Description of the Related Art
Blow-by gas is gas leaked from a combustion chamber of an engine to a crankcase, and such blow-by gas is generated mostly in a compression stroke and partly in an expansion stroke.
Since the blow-by gas is a main cause of air pollution, the blow-by gas is forcibly supplied to an intake manifold by a closed crankcase ventilation (CCV) apparatus and is re-burned.
Referring to FIG. 6 to FIG. 8, a conventional CCV apparatus will be described.
As shown in FIG. 6, according to a conventional CCV apparatus, a middle case 23 is coupled to a lower case 13, and an upper case 20 is coupled to an upper portion of the middle case 23.
The lower case 13 has a cylindrical shape, a lower end of the lower case 13 is connected to a withdrawal pipe 15, and the withdrawal pipe 15 is connected to an oil pan (not shown).
The middle case 23 includes a body 32 mounted in the lower case 13, an upper plate 29 coupled to an upper end of the body 32, and a cup 27 formed on an upper surface of the upper plate 29.
A blow-by gas passageway 25 penetrates a middle portion of the upper plate 29, and a filter 30 is mounted at a lower portion of the blow-by gas passageway 25. The filter 30 filters engine oil contained in the delivered blow-by gas, and the filtered engine oil is withdrawn to the oil pan (not shown) disposed at a lower portion of an engine through the withdrawal pipe 15.
The upper plate 29 blocks flow of blow-by gas between the cup 27 and the body 32 except flow of blow-by gas through the blow-by gas passageway 25. In addition, a gas hole 70 is formed at the upper plate 29 and outside the cup 27, and the gas hole 70 exhausts to the exterior of the cup 27 the blow-by gas that is filtered by the filter 30 and stored in the body 32.
A first elastic member 35 is mounted at an exterior circumference of an upper portion of the blow-by gas passageway 25.
The cup 27 is formed on the upper surface of the upper plate 29, and an inlet pipe 5 for receiving blow-by gas from the crankcase and an outlet pipe 10 for supplying filtered or detoured blow-by gas to the intake manifold are formed at a side external surface of the cup 27. The inlet pipe 5 and the outlet pipe 10 are coupled to the upper end of the lower case 13. The inlet pipe 5 is fluidly-communicated with the inside of the cup 27 such that blow-by gas in the crankcase flows into the cup 27. The outlet pipe 10 is fluidly-communicated with the inside of the cup 27 through the gas hole 70. Therefore, blow-by gas in the cup 27 does not directly flow to the outlet pipe 10. Instead, blow-by gas in the cup 27 flows to the outlet pipe 10 through the gas hole 70 after being filtered.
In addition, the cup 27 is provided with a diaphragm 40 for covering an opening formed at an upper end of the cup 27. The diaphragm 40 is disposed apart from an upper portion of the blow-by gas passageway 25 by the first elastic member 35.
The upper case 20 is configured to enclose the upper end of the cup 27. The upper case 20 has a hollow such that the diaphragm 40 moves upwardly or downwardly therein, and a second elastic member 50 is interposed between the upper case 20 and the diaphragm 40.
As shown in FIG. 7, a by-pass hole 60 is formed at the upper end of the cup 27. When the diaphragm 40 covers the opening at the upper end of the cup 27, the by-pass hole 60 is blocked and blow-by gas in the cup 27 is not detoured to the outlet pipe 10. However, when the blow-by gas received from the inlet pipe 5 is sufficiently enough to detach the diaphragm 40 from the upper end of the cup 27 by overcoming the second elastic member 50, the by-pass hole 60 is opened and blow-by gas in the cup 27 flows to the outlet pipe 10 through the by-pass hole 60 as shown in FIG. 9. The by-pass hole 60 prevents pressure in the crankcase from excessively increasing.
In addition, an indicator 55 is mounted on a portion of an upper end of the diaphragm 40. The indicator 55, together with the diaphragm 40, moves upwardly or downwardly and displays degradation of the filter 30.
As shown in FIG. 8, in a case in which pressure in the crankcase is not high, the diaphragm 40 blocks the by-pass hole 60 and blow-by gas is exhausted to the outlet pipe 10 through the gas hole 70 after being filtered by the filter 30.
As shown in FIG. 9, in a case in which pressure in the crankcase is high, the diaphragm 40 moves upwardly by pressure of the blow-by gas and opens the by-pass hole 60. Therefore, a part of blow-by gas in the cup 27 is directly exhausted to the outlet pipe 10 through the by-pass hole 60.
According to the conventional CCV apparatus, since the first elastic member 35 for controlling pressure in the crankcase and the second elastic member 50 for controlling the by-pass operation apply elastic force together to the diaphragm 40, tuning of the first and second elastic members 35 and 50 for preferable operation of the diaphragm 40 may be difficult due to the nonlinearity of the first and second elastic members 35 and 50. In addition, when blow-by gas is detoured, the rubber material of the diaphragm may move quickly and be damaged.
As shown in FIG. 7, since the by-pass hole 60 is formed at the upper end of the cup 27, it is difficult for the area of the by-pass hole 60 to be enlarged. Therefore, the cross-sectional area of the by-pass hole 60 is smaller than that of the blow-by gas passageway 25 and thus a small amount of blow-by gas may be detoured. Therefore, pressure in the crankcase is reduced slowly as shown in FIG. 5. In addition, since the diaphragm of a rubber material operates as a valve, air-tightness may deteriorate.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.